package service

import (
	"crypto/rand"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"math"
	"strconv"
	"strings"
	"time"

	"gorm.io/gorm"
	"wails-app/internal/dao"
	vehicleRequest "wails-app/internal/model/vehicle/request"
	"wails-app/internal/modules/central-payment/model/request"
	centralRepo "wails-app/internal/modules/central-payment/repository"
	paymentService "wails-app/internal/modules/payment/service"
	utils "wails-app/internal/pkg"
	vehicleService "wails-app/internal/service/vehicle"
)

const (
	PaymentEntryCentral = "central_payment_machine"
	tokenLifetime       = 30 * time.Minute
)

type Service struct {
	repo       *centralRepo.Repository
	vehicleSvc *vehicleService.VehicleService
}

func New() *Service {
	return &Service{repo: centralRepo.New(), vehicleSvc: &vehicleService.VehicleService{}}
}

func tokenHash(token string) string {
	digest := sha256.Sum256([]byte(token))
	return hex.EncodeToString(digest[:])
}

func randomToken() (string, error) {
	bytes := make([]byte, 32)
	if _, err := rand.Read(bytes); err != nil {
		return "", err
	}
	return hex.EncodeToString(bytes), nil
}

func (s *Service) Login(req request.LoginRequest) (string, error) {
	username := strings.TrimSpace(req.UserName)
	if username == "" || req.Password == "" {
		return "", errors.New("用户名或密码不能为空")
	}
	device, err := s.repo.FindDeviceByUsername(username)
	if err != nil || !device.Enabled || !utils.BcryptCheck(req.Password, device.PasswordHash) {
		return "", errors.New("用户名或密码错误")
	}
	token, err := randomToken()
	if err != nil {
		return "", fmt.Errorf("生成设备令牌失败: %w", err)
	}
	if err := s.repo.ReplaceTokens(device.DeviceID, &dao.CentralPaymentToken{
		DeviceID: device.DeviceID, TokenHash: tokenHash(token), ExpireAt: time.Now().Add(tokenLifetime),
	}); err != nil {
		return "", fmt.Errorf("保存设备令牌失败: %w", err)
	}
	return token, nil
}

func (s *Service) Authenticate(token string) (*dao.CentralPaymentDevice, error) {
	if strings.TrimSpace(token) == "" {
		return nil, errors.New("Token不能为空")
	}
	device, err := s.repo.FindDeviceByTokenHash(tokenHash(token), time.Now())
	if err != nil {
		return nil, errors.New("Token无效或已过期")
	}
	return device, nil
}

func stopTimeText(minutes int64) string {
	if minutes < 60 {
		return fmt.Sprintf("%d分钟", minutes)
	}
	return fmt.Sprintf("%d小时%d分钟", minutes/60, minutes%60)
}

func moneyString(amount float64) string {
	return strconv.FormatFloat(amount, 'f', 2, 64)
}

func parseMoney(raw json.RawMessage) (float64, error) {
	value := strings.TrimSpace(string(raw))
	if len(value) >= 2 && value[0] == '"' && value[len(value)-1] == '"' {
		if err := json.Unmarshal(raw, &value); err != nil {
			return 0, errors.New("Money格式错误")
		}
	}
	amount, err := strconv.ParseFloat(strings.TrimSpace(value), 64)
	if err != nil || math.IsNaN(amount) || math.IsInf(amount, 0) || amount < 0 {
		return 0, errors.New("Money必须是非负金额")
	}
	return amount, nil
}

func moneyEqual(left, right float64) bool {
	return math.Abs(left-right) < 0.005
}

func paymentMethod(payType int) (string, error) {
	switch payType {
	case 0:
		return paymentService.PaymentCash, nil
	case 1:
		return paymentService.PaymentPOS, nil
	default:
		return "", errors.New("PayType仅支持0(现金)或1(刷卡)")
	}
}

type Price struct {
	OrderID  string
	CarNo    string
	InTime   time.Time
	OutTime  time.Time
	StopTime string
	Price    string
}

func (s *Service) QueryPrice(device *dao.CentralPaymentDevice, carNo string) (*Price, error) {
	carNo = strings.TrimSpace(carNo)
	if carNo == "" {
		return nil, errors.New("CarNo不能为空")
	}
	preview, err := s.vehicleSvc.ExitPreview(vehicleRequest.ExitPreviewRequest{PlateNumber: carNo})
	if err != nil {
		return nil, err
	}
	if preview.TicketNo == "" || preview.TicketState != "pending_payment" || preview.PaymentStatus != "unpaid" {
		return nil, errors.New("当前订单不允许缴费")
	}
	if device != nil && device.ParkingLotID != 0 && device.ParkingLotID != preview.ParkingLotID {
		return nil, errors.New("设备无权查询该停车场订单")
	}
	now := time.Now()
	return &Price{
		OrderID: preview.TicketNo, CarNo: preview.PlateNumber,
		InTime: time.Unix(preview.EntryTime, 0), OutTime: now,
		StopTime: stopTimeText(preview.StayTime), Price: moneyString(preview.Fee),
	}, nil
}

func (s *Service) PaySuccess(device *dao.CentralPaymentDevice, req request.PaySuccessRequest) error {
	if req.Data.PayDev != 2 {
		return errors.New("PayDev必须为2(POF)")
	}
	// Token authentication already binds the request to a central payment
	// device. DevId is retained as a protocol/audit field and is deliberately
	// non-blocking because vendor hardware identifiers may differ from the
	// management-system device_id.
	method, err := paymentMethod(req.Data.PayType)
	if err != nil {
		return err
	}
	money, err := parseMoney(req.Data.Money)
	if err != nil {
		return err
	}
	orderID := strings.TrimSpace(req.Data.OrderID)
	carNo := strings.TrimSpace(req.Data.CarNo)
	if orderID == "" || carNo == "" {
		return errors.New("OrderId和CarNo不能为空")
	}

	ticket, err := s.repo.FindTicket(orderID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return errors.New("订单不存在")
		}
		return err
	}
	if ticket.PlateNumber != "" && ticket.PlateNumber != carNo {
		return errors.New("OrderId与CarNo不匹配")
	}

	entry := device.PaymentEntry
	if entry == "" {
		entry = PaymentEntryCentral
	}
	if ticket.State == "paid" {
		if !s.matchesExistingPayment(ticket, entry, method, money) {
			return errors.New("订单已支付，支付数据不一致")
		}
		return nil
	}
	if ticket.State != "pending_payment" {
		return fmt.Errorf("订单当前状态不允许支付: %s", ticket.State)
	}

	preview, err := s.vehicleSvc.ExitPreview(vehicleRequest.ExitPreviewRequest{SessionID: ticket.VehicleRecordID})
	if err != nil {
		return fmt.Errorf("重新计算订单费用失败: %w", err)
	}
	if preview.TicketNo != orderID || preview.PlateNumber != carNo {
		return errors.New("订单对应的在场车辆不匹配")
	}
	if device.ParkingLotID != 0 && device.ParkingLotID != preview.ParkingLotID {
		return errors.New("设备无权支付该停车场订单")
	}
	if !moneyEqual(preview.Fee, money) {
		return errors.New("金额已变化，请重新查询")
	}
	if err := s.vehicleSvc.PayDigitalTicket(orderID, entry, method, "", money, 0); err != nil {
		// A retry can race with the first notification. Re-read the order so a
		// successful first payment is reported as an idempotent success.
		if current, findErr := s.repo.FindTicket(orderID); findErr == nil && current.State == "paid" && s.matchesExistingPayment(current, entry, method, money) {
			return nil
		}
		return fmt.Errorf("写入数字票支付状态失败: %w", err)
	}
	return nil
}

// PayStatus returns the persisted ticket state without recalculating or
// mutating payment data. It is intended for payment-machine retry/reconcile
// flows after a paysuccess response was lost.
func (s *Service) PayStatus(device *dao.CentralPaymentDevice, req request.PayStatusRequest) (*dao.DigitalTicket, *dao.VehicleRecord, error) {
	orderID := strings.TrimSpace(req.Data.OrderID)
	carNo := strings.TrimSpace(req.Data.CarNo)
	if orderID == "" {
		return nil, nil, errors.New("OrderId不能为空")
	}
	ticket, err := s.repo.FindTicket(orderID)
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, nil, errors.New("订单不存在")
		}
		return nil, nil, err
	}
	if carNo != "" && ticket.PlateNumber != "" && ticket.PlateNumber != carNo {
		return nil, nil, errors.New("OrderId与CarNo不匹配")
	}
	record, err := s.repo.FindVehicleRecord(ticket.VehicleRecordID)
	if err != nil {
		return nil, nil, errors.New("订单对应的停车记录不存在")
	}
	if device.ParkingLotID != 0 && device.ParkingLotID != record.ParkingLotID {
		return nil, nil, errors.New("设备无权查询该停车场订单")
	}
	return ticket, record, nil
}

func (s *Service) matchesExistingPayment(ticket *dao.DigitalTicket, entry, method string, money float64) bool {
	payment, err := s.repo.FindLatestPayment(ticket.VehicleRecordID, entry)
	return err == nil && payment.PaymentMethod == method && moneyEqual(payment.Amount, money)
}

// Log persists protocol metadata for field troubleshooting. The caller must
// pass a redacted body: device tokens and login passwords must never be saved.
func (s *Service) Log(endpoint, deviceID, sourceIP string, body interface{}, result int, remark string) {
	payload, err := json.Marshal(body)
	if err != nil {
		payload = []byte("{}")
	}
	s.repo.Log(&dao.CentralPaymentRequestLog{
		Endpoint: endpoint, DeviceID: deviceID, SourceIP: sourceIP,
		RequestBody: string(payload), Result: result, Remark: remark,
	})
}